This is not a good thing. Topiramate is an anti-epileptic drug which has the side effect of reduced appetite. It also has the side effect of making people stupid. According to MedPage Today,

Topiramate, an anti-epileptic, is known to cause suicidal thoughts; however, there were no suicide attempts or suicidal behaviors in the company’s trial of the combination product.

Topiramate is also linked to impaired attention and concentration, memory loss, slowed thinking, and language difficulties, and adding phentermine to the mix didn’t seem to mitigate those cognitive issues. Patients taking the combination were four times more likely to experience a cognitive disorder compared with placebo. The issues went away once patients stopped taking the drug.

I’ve taken topiramate and that is exactly what it did. Some people can take high doses without severe effects but I had side effects on a very low dose. Not enough to reduce my appetite but certainly enough to affect attention and thinking. I hate to imagine what would have happened on a higher dose.